Studies have looked exclusively at the relationship between cardiovascular disease and sFLC concentrations. Kurt et al. [756] reported higher sFLC concentrations in patients with heart failure, and a reduction after treatment with a novel therapeutic (levosimendan), although no relationship was found with the degree of heart failure. Jackson et al. [864] used a novel assay, Combylite®, to measure combined concentrations of κ and λ sFLCs (cFLC) in patients hospitalised with decompensated heart failure (n=628). Individuals with cFLC concentrations within the upper quartile had a higher risk of death than those with concentrations in the lowest quartile (HR 2.4; p<0.0001); this remained significant after adjusting for other established risk factors (HR 1.49; p=0.001).

Moreover, the combination of cFLC with B-type natriuretic peptide (BNP), a gold standard biomarker for heart failure, stratified patients into four groups with a low to high risk of mortality. Patients with both an elevated BNP (>441 pg/ml) and cFLC (>51.8 mg/L) concentration were at the greatest risk of mortality (Figure 35.3). A similar observation was reported in patients with acute heart failure, in which cFLC were associated with risk of mortality or hospitalisation [865].